The present disclosure relates to a composite guide vane. Further, the present disclosure relates to a gas turbine structure. Moreover, the present disclosure relates to a gas turbine engine. Furthermore, the present disclosure relates to an aeroplane.
A gas turbine engine may be used as a jet engine. The term jet engine includes various types of engines, which admit air at relatively low velocity, heat it by combustion and shoot it out at a much higher velocity.
Accommodated within the term jet engine are, for example, turbojet engines and turbo-fan engines. The invention will below be described for a turbo-fan engine, but may of course also be used for other engine types.
A gas turbine structure, which may sometimes be denoted a case or frame, is used for supporting and carrying bearings, which in turn, rotatably support rotors. Conventional turbo fan engines have a fan frame, a mid-frame and an aft turbine frame. These frames constitute a gas turbine structure including a first housing, a second housing and a strut or a vane having a first end of the strut or vane being attached to the first housing and a second end being attached to the second housing. A vane or strut may be made of a composite material.
In order to achieve the attachment of the strut or vane to the first housing and the second housing, respectively, U.S. Pat. No. 5,320,490 proposes the use of linking braces each one of which connecting a corner of a composite vane to the first or second housing. However, the '490 solution implies that the corners of the composite vane may be subjected to large stresses.
It is desirable to provide a composite guide vane which overcomes or ameliorates at least one of the disadvantages of the prior art, or to provide a useful alternative.
As such, the present disclosure relates to a composite guide vane for a gas turbine structure. The guide vane is adapted to extend in a guide vane direction from a first housing towards a second housing of the gas turbine structure. Moreover, the guide vane has a guide vane length in the guide vane direction and the guide vane comprises a first attachment portion with at least one first opening for attachment of the guide vane to the first housing of the gas turbine structure. The first opening extends in a first opening direction which forms an angle with the guide vane direction.
The guide vane further comprises a first guide vane centre point which is a point halfway between the leading edge and the trailing edge along the mean camber line which point is adapted to be located closest to the first housing. Moreover, the guide vane further comprises a second guide vane centre point which is a point halfway between the leading edge and the trailing edge along the mean camber line which point is adapted to be located closest to the second housing.
As used herein, the expression “guide vane direction” relates to the direction from the first guide vane centre point to the second guide vane centre point. In a similar vein, as used herein, the expression “guide vane length” relates to the distance between the first guide vane centre point and the second guide vane centre point.
Generally, an opening has an opening axial extension and an opening circumferential extension. As used herein, the expression “first opening direction” relates to a direction parallel the opening axial extension.
Furthermore, the guide vane comprises a cover portion comprising a first material and a core portion which is at least partially enclosed by the cover portion. The core portion comprises a second material which is different from the first material. Further, the guide vane comprises a leading edge and a trailing edge and the guide vane extends from the leading edge to the trailing edge along a mean camber line.
As used herein, the expression “mean camber line” relates to the locus of points halfway between a suction side and a pressure side of the guide vane as measured perpendicular to the mean camber line itself. The extension of the mean camber line in relation to the guide vane direction will be described with reference to FIG. 5 hereinbelow.
Moreover, the guide vane comprises a chord length being the distance from the leading edge to the trailing edge along the mean camber line. The guide vane comprises a first chord length at a first position in the guide vane direction and a second chord length at a second position in the guide vane direction. Further, second position is located at a first distance from the first opening in the guide vane direction and the first position is located at the first opening or between the first opening and the second position in the guide vane direction. The first distance is less than or equal to 0.15 of the guide vane length.
According to the present disclosure, the ratio between the first chord length and the second chord length greater than or equal to 1.10, preferably greater than or equal to 1.15.
A guide vane generally has a vane thickness, i.e. an extension in a direction perpendicular to the mean camber line, which: is relatively small at the leading edge, increases in a first portion of the vane along the mean camber line and then decreases in a second portion of the vane so as to be relatively small at the trailing edge. It is often desired that the opening or openings for the attachment of the vane to the first housing are located at a distance from the leading edge and trailing edge, respectively, such that the opening or openings are provided in a portion of the first attachment portion which have an appropriate vane thickness.
However, it is generally not desired to put the opening or openings too far from the leading edge and trailing edge, respectively, since this may result in an attachment of the guide vane to the first housing which does not provide a sufficient stiffness. This is since the openings or openings may in such cases be located too close to a guide vane centre line, i.e. a line extending halfway between the leading edge and the trailing edge.
The guide vane according to the present invention is wider at the first position, i.e. at a location closer to the attachment opening or openings, than the second position. This implies that the first attachment portion of the guide vane of the present disclosure, or at least a portion thereof, may be wider as compared prior art guide vanes.
The wider first attachment portion implies that the opening or openings may be located in a portion of the guide vane which has an appropriate thickness. Moreover, the opening or openings may nevertheless be located at an appropriate distance from the guide vane centre line such that a desired stiffness may be obtained.
As such, by the widening of the first attachment portion as described hereinabove, an appropriate local strength of the opening or openings for attachment members, such as bolts, rivets or the like, is obtained at the same time as an appropriate stiffness of the attachment of the guide vane to the first housing is obtained.
Moreover, since the widening of the first attachment portion occurs over 15% or less of the guide vane length, the widening will not, at least not to any greater extent, have a negative influence on the aerodynamic properties and/or the weight of the guide vane.
According to the present disclosure, the guide vane may comprise a first leading edge point on the mean camber line of the first position and a second leading edge point on the mean camber line of the second position. Moreover, the guide vane may comprise a first intermediate point located at a position on the mean camber line of the first position such that a first line between the first intermediate point and the second leading edge point will extend in a direction which is parallel to the guide vane direction. Furthermore, the guide vane may have a leading edge distance which is the distance from the first intermediate point to the first leading edge point along the mean camber line. The leading edge distance may be at least 10%, preferably at least 15%, of the second chord length.
A portion of the guide vane which is located close to the leading edge may in many implementations be imparted structural loads which are larger than loads imparted on the trailing edge portion of the guide vane. Consequently, it may be preferred to implement the widening of the guide vane such that at least a portion of the additional chord length is located at the leading edge of the guide vane.
According to the present disclosure, the guide vane may comprise a first trailing edge point on the mean camber line of the first position and a second trailing edge point on the mean camber line of the second position. Moreover, the guide vane may comprise a second intermediate point located at a position on the mean camber line of the first position such that a second line between the second intermediate point and the second trailing edge point will extend in a direction which is parallel to the guide vane direction. Furthermore, the guide vane may have a trailing edge distance being the distance from the second intermediate point to the first trailing edge point along the mean camber line. The trailing edge distance may be at least 10%, preferably at least 15%, of the second chord length.
According to the present disclosure, the core portion may have an extension which terminates before the first opening. As such, the first opening may be delimited by the cover portion but not the core portion. In implementations of the composite guide vane, the first material, which forms at least a part of the cover portion, generally has structural characteristics which are better than the structural characteristics of the second material, which forms at least a part of the core portion. Purely by way of example, the first material may have a yield stress and/or modulus of elasticity which is higher than the yield stress and/or modulus of elasticity of the second material.
As such, implementations of the guide vane wherein the first opening is delimited by the cover portion may result in an increased strength of the attachment of the guide vane to the first housing. Optionally, or in addition, implementations of the guide vane wherein the first opening is delimited by the cover portion may result in that the thickness of the guide vane at the location of the first opening may be reduced as compared to prior art composite guide vanes.
According to the present disclosure, the first opening may be located a first opening distance from the leading edge along the mean camber line. Moreover, the first opening distance may be at least 5%, preferably at least 10%, of the first chord length.
According to the present disclosure, the first attachment portion may comprise a plurality of openings. Moreover, each one of the openings may be located at a distance from the leading edge along the mean camber line of at least 5%, preferably at least 10%, of the first chord length.
According to the present disclosure, the first attachment portion may comprise a plurality of openings. Moreover, each one of the openings may be located at a distance from the trailing edge along the mean camber line of at least 5%, preferably at least 10%, of the first chord length.
According to the present disclosure, the guide vane may further comprise a second attachment portion comprising at least one second opening for attachment of the guide vane to the second housing of the gas turbine structure. The guide vane may comprise a third chord length at a third position in the guide vane direction and a fourth chord length at a fourth position in the guide vane direction. Furthermore, the fourth position may be located at a second distance from the second opening in a direction opposite to the guide vane direction and the third position may be located at the second opening or between the second opening and the fourth position in a direction opposite to the guide vane direction. The second distance may be less than or equal to 0.15 of the guide vane length. Furthermore, the ratio between the third chord length and the fourth chord length may be greater than or equal to 1.10, preferably greater than or equal to 1.15.
According to the present disclosure, the first material may be a composite material such as a carbon fibre reinforced polymer.
According to the present disclosure, the second material may be a structural core material such as a foam or a honeycomb core material.
A second aspect of the present disclosure relates to a gas turbine structure comprising a first housing, a second housing and a guide vane according to the first aspect of the present disclosure.
According to the second aspect of the present disclosure, the gas turbine structure may further comprise a flow passage between the first housing and the second housing. Moreover, the gas turbine structure may further comprise a flow passage delimiting member which is positioned such that the first attachment portion is separated from the flow passage.
The guide vane may comprise a leading edge flow passage point being the point on the leading edge which is located closest to the flow passage delimiting member in the guide vane direction. Moreover, the guide vane may further comprise a trailing edge flow passage point being the point on the trailing edge which is located closest to the flow passage delimiting member in the guide vane direction.
A third aspect of the present disclosure relates to a gas turbine engine comprising a gas turbine structure according to the second aspect of the present disclosure.
A fourth aspect of the present disclosure relates to an aeroplane comprising a gas turbine engine according to the third aspect of the present disclosure.
Further advantages and advantageous features of the invention are disclosed in the following description and in the dependent claims.